1. Field of the Invention
The present invention relates generally to an imaging apparatus and an image processing method, and more particularly, to an imaging apparatus and processing method which perform JPEG compression encoding by dividing an image after an image processing into a plurality of blocks without an external memory, perform efficient JPEG compression encoding, and generate a natural compressed image.
2. Description of the Related Art
An image compression encoding in a JPEG mode processes one entire screen as one unit. On the other hand, one image is divided into a plurality of blocks in a vertical direction and the divided blocks are processed in order to save capacities of a line memory, within Large Scale Integration (LSI) installed in a digital still camera and the like. Accordingly, in order to process one entire image and then make the image be in a JPEG compressible state, it is required to stop processing for all blocks and record a result of the processing in an external memory such as an SDRAM to combine the blocks and the result of the processing.
Further, a JPEG compression encoder for JPEG compression reads an image configured in an external memory to execute compression encoding. To this end, JPEG compression in a digital still camera is performed through a process of recording one image in an external memory such as an SDRAM at all times and also reading the image from the corresponding external memory.
In many cases, speed capability of a conventional digital still camera is determined by speed capability of an imaging apparatus. Further, the speed capability of the digital still camera requires only a continuous shooting capability in a degree of three frames/shots to seven frames/shots per second. However, current imaging apparatuses have a high capability, and there is a trend of using a resolution of 12 to 20 megapixels or more. Further, currently, the speed capability requires a continuous shooting capability in a degree of 10 to 15 frames/shots per second, and a processing capability required for the digital still camera becomes much higher in comparison with the conventional camera.
Since the processing capability becomes higher as described above, the digital still camera repeatedly reads the image from the external memory or writes the image in the external memory every time for JPEG compression encoding of the image. Further, accordingly, power consumption increases, the number of external memories, which are installed to solve a problem of decrease in speed, increases according to the increase in the reading and writing, and a price of the digital still camera increases according to the increase in the number of external memories. Therefore, a need exists to execute the JPEG compression encoding of the image without performing the reading from and the writing in the external memory as much as possible.
Meanwhile, JPEG compression encoding is an encoding based on DCT, and has to be encoded only in the units of eight vertical pixels. In general, when the lowest part of the image does not completely include eight pixels, a method of encoding the lowest part by copying a final line or inserting a black line is used. However, when the lowest part is encoded by copying the final line or inserting the black line, a problem is created in that an image corresponding to the lowest part is not a natural image.